ASKOCOAT 2K PU resins for controlled release fertilizers

ASK Chemicals offers a 2K PU resin system for the production of polymer coated controlled release fertilizers based on all kind of granules.

The patented coating system consists of two components, a polyol and an isocyanate. The polyol is a modified solvent-free polyol formulation containing more than 60 % renewable raw materials. The isocyanate component is a modified isocyanate formulation including a bench life extender to achieve a controllable reaction in the mixing equipment. Both components are solvent-free and contain only reactive ingredients to prevent leach out of coating chemicals into the soil.

The fertilizer granules are coated at ambient to moderate temperatures in a drum mixer. Therefore, also granules with lower melting points like urea, can be coated with this technology. The resin system shows a homogeneous distribution without any defects on all kind of granules. The curing reaction takes place by a polyaddition reaction and is catalyzed by addition of a gaseous or liquid amine to the resin system. Using a liquid amine with high flash points prevents the use of ATEX equipment. A spray curing process secures optimal catalyst distribution. The coatings process is very fast and efficient, the typical curing time for one layer is below two minutes to be tack free.